Several publications are referenced in this application by numerals in parentheses in order to more fully describe the state of the art to which this invention pertains. Full citations for these references are found at the end of the specification. The disclosure of each of these publications is incorporated by reference herein.
This year prostate cancer is expected to be diagnosed in 200,000 men in the U.S. and to result in the loss of 38,000 lives. Such numbers make prostate cancer the most frequently diagnosed malignancy (other than that of the skin) in American males and the second leading cause of cancer-related death in that group. Physicians usually detect cancers by finding a lump in the prostate gland, which is a walnut shaped structure that helps to maintain the viability of sperm. Such lumps may be discovered during a routine checkup or an examination prompted by a patient's complaint of sudden urinary discomfort, or occasional impotence.
Prostate specific antigen (PSA) is one of the original molecular markers utilized for the diagnosis of prostate cancer. When an elevation of PSA is found in the serum, prostate cancer is likely (1). The ratio of free PSA/total PSA (f/t) can be used to diagnose prostate cancer more accurately in men whose PSA is elevated (2-4). If the f/t ratio is below 7% the likelihood is that the patient has cancer; if f/t is above 25%, no cancer is probably present.
Recently, another marker, prostate specific membrane antigen (PSAMA) has been introduced. PSMA is also of prognostic significance, with elevation correlating well with more advanced cancer (5).
It should be noted that use of these PSA molecular markers in evaluating men with possible prostate cancer still requires biopsy of the suspected mass for a definitive diagnosis. In light of the invasiveness of this procedure, less intrusive means for assessing patients for prostate cancer are actively being sought.